The present invention relates to a multimedia recording system for recording multimedia data created from an object. More particularly, the present invention relates to a multimedia recording system capable of verifying whether or not the multimedia data created from the object belongs to the intended object.
There has been generally known a multimedia recording system which downloads multimedia data sent from devices, capturing various multimedia data such as a digital camera, into a personal computer for example to record the captured multimedia data.
Since processing or falsification of digital data is easy, there are growing needs for an authentication of the data in the multimedia recording system. Already, there has been proposed a digital camera which applies an electronic signature to data of a photographed image so as to authenticate that the image has not been falsified, or the image has been taken by a particular camera.
For example, JP H11-220686A discloses a technology wherein, when a shutter button is pressed, a CPU (central processing unit) acquires the time from a timer, stores the acquired time to a RAM (random access memory) and simultaneously obtains data of a photographed image from a CCD (charge-coupled device) to accommodate the obtained image data in the RAM, and compresses the accommodated image data. Then, the CPU retrieves a sequence number from an EEPROM (electrically erasable programmable read-only memory), adds 1 (one) to the retrieved sequence number, records the sequence number to which 1 is added to the retrieved sequence number on the EEPROM, and adds the sequence number and data on the time to the top of the compressed image data. The CPU further calculates a message digest function with respect to thus obtained image information by utilizing a massage digest function algorism, retrieves a private key from the EEPROM, encrypts the message digest function, adds an obtained signature to the end of the image information to define a set of photographing information, and records the photographing information on an external memory.
JP 2000-125237A discloses a technology of a digital camera which stores a signal of a photographed image digitally. According to the disclosed technology, a mode dial is set to a registration position, and under control of a CPU, a password is entered based on a selection of desired characters by sequentially changing a character displayed on a display device, one by one, with an arrow button. Then, the CPU inputs the password into a data memory. When a photographing button is pressed in the state in which the password is inputted in the data memory, the image signal from an imaging unit is transmitted to an A/D (analog/digital) converter and is digitalized to be image data. Thereafter, the image data is associated with the inputted password, and is stored into the data memory together with the password.
Also, JP 2000-299847A proposes a technology wherein a digital camera sends information endemic to own to a host computer, and the host computer generates a cryptography key based on the received endemic information, and sends the created cryptography key to the digital camera. The digital camera then encrypts data of a photographed image based on the received cryptography key.
However, in the conventional multimedia recording systems, it is not possible to verify validity of a photographic object. In other words, the conventional multimedia recording systems cannot verify whether or not the photographed contents belong to the intended photographic object.